Harold, 24, has played in all 48 games in his career and started 24 over the last two seasons, tallying 71 tackles and 5.0 sacks. A third-round pick in 2015, he was pegged as a pass rusher coming out of Virginia, but he has just 5.0 sacks and 14 quarterback hits in his career.

Dekoda Watson, who has 4.0 career sacks in eight years primarily spent as a special teamer, has been working with the 49ers' second team behind Harold.

Harold is expected to provide depth at strongside linebacker in Detroit behind free agent signee Devon Kennard, who started camp on the non-football injury list before being activated Aug. 1.